Brake and sanding control apparatus



Sander Aug. 24, 1948. G/K. NEWELL BRAKE AND SANDING CONTROL APPARATUS Filed March 3, 1945 Brake Iii/0e Vern Vblue w 6 017 ding Reservoir ioa flO . 5 Sandezs 0n oiher side 0/ Sander Direezz'on of frame] 5 Sheets-Sheet 1 Hull} end ofCar' INVENTOR. George KNewell ATTORNEY Aug. 24, 1948. NEWELL BRAKE AND smnms common APPARATUS 5 Sheets-Sheet 3 Filed March 5, 1945 Confrol Pz'geg vzm Vblve Mechanism Zz'nder Brake Cy To oiher I end of Car INVENTOR. George K. NeweZZ Aug. 24, 1948. NEWELL 2,447,713

BRAKE AND SANDING CONTROL APPARATUS Filed March 3, 1945 Sheets-Sheet 4 Brake Value Vnl U8 Mechanism Brain's q lznder 147 (24 149 Sandzng Control 154 Valve Sanding Reservoir gg q 155 151 W; 19 152 146 3 a 156 Ho {57 158 7b Sanders L To Sanders INVENTOR. I Gear ge K Newell BY fl fi 4 ATTORNEY Aug. 24, 1948. NEWELL 2,447,713

BRAKE AND SANDING CONTROL APPARATUS Filed March 3, 1945 5 Sheets-Sheet 5 \L\ 28g- I 157 157 26 16Ab 42a '54 159 150 155 v INVENTOR. George KNewell BY fi q 1M AT TOPNEY Fatenteci Aug. 24, 1948 PAT smnennh smnme Generate APPARATUS George i-Newell-l-near Pitcairn; Pai-,-assigiiory -to; The westing house" Brake- Company, Wilmerding, Pa.,'a corporation of Pennsylvania. Aipplieatiofl 3*, 1945; Si'iiiFNdSSlLflflW 1 This invention relate's to brake andsa-ndi-ng control apparatus --for-' vehicles, suel'ras railway cars and trainsjand has particul'a'r relation td the automatidcontrol 0f the brakes associated==with the vehicle wheelsin a manner topreiren-t slidingthereof dueto excessive braking-forces as well' as tothe automatic sanding? of the rails in response toa slipping condition of the wheels.

As employedherein-the term slipping or slip'-- ping condition andsimilar variant-s"refersto the rotation: of the-vehicle wheel at aspee'rl diffiering from that conresponding to the speed -ofthe vehicle at a given inst/anti As is well known; a

slipping con'dition' of a-vehicle-wheel may be im-- du'cedeither by excessive propulsion--toro1ue;=in: which casethe wheel rotatesat a speed "higher" than that corresponding to vehicle speed; or induced by .excessivebraking forced-n which case the wheelrotates 'at-a* speed less-than that cor responding to vehicle speed;- In thepr'esent ap .plication theapparatus to-=be described-relates to brake control= and the term slipping will ther-e fore refer to" rotation ofthe-vehiclewheel at a speedless than-that -corresponding= to vehicle-- speed unlessotherwiseindicatedv- A When the braking forces exerted em a vehiclewheel while-the -vehicle-isdemotion-are such# as to exceed or overcome-the adhesion between the wheel-and-the rail 'or road' surface onwhichthe wheel rolls,-thewheel instantly-hegins to' decelerate'at an alonormally rapid i ate toward a zero speedor lockedcondition. If the wheel 'redudes in spe'ed'to the locked' er admaaeve' 'oii dition, it is'dra'g'ged along thera'il or"?? face; In thepreseht appli c'atiohthi'sfsdesi'ghat (If as a slidingcoridition? The two 'terrifs "slipping and sliding and their respectivevariaritsf are accordingly not synonymousih'hieanihgarfd' the 'distinction'betweeh thesete'rins mustbe hdr'ne in mindin reading the subsequent description of my invention. a

Sliding of railway car wheels-has lon'g'*?bee"ria' problem which the railroadshave sou'gh- 0 so ve for the re'asonthat sliding'of 'c'air wheels-produces flat spots on the wheels and t'entls leifgthe'n the stopping distance of the trai repair andreplacement of the flat wheels ite'mof maintenance whichthe' 1 railroadsnane; to eliminate. Numerous proposalsarid devices have been: made and employed for detectirig"the 5'0" incipiency or: imminence of a slidin'g'rcohditioII-of the wheels on the b'as'isoi the abnormal rate or: deceleration of 'a vehicle wheel I w'l'iile it' is in 'a; slipping condition prior to: actually-becoming locked andsliding;

have been of an -electrical-oramechanical *nature' and having functioned torapidly reduce the degree of applicatiorr'of 'the hrakes ona slipping wheel sufficiently toinsure the restoration "ofthe wheel hack to a speedcorresponding" to vehicle speed-,--without permit-ting thewheel to reduce sufliciently in speed so as to become locked'an-cl slide-and then toreapply thebr-akes onthe wheel whichslippedzv Once a vehicle wheel begins to; slip "during a given brake application; ii'ris-likely that the relation eithehraking forces reapplied on the wheel to theadhesion' between the wheel andthe rail following *the slipping condition will continue to' be suchas' to induce recurrent-orrepeated slipping cycles, which although tolerable-are at the same time undesirabler V Insome-instanoes; it has Been proposed to provide apparatus ion automatically reducing: the degree otthebraliingwtorces reapplied toa; wheel that slips inordertomini-mizethe' possibility ofrecur-rent or repeated slipping cycles.- Sucl1-devices, while performing the objective of prevent ing -recurrentslippirrg; cycles-;- nevertheless provide ai -penalty the ay, of reduced braking forces resulting inpossible lengthening of train e ma d ease-r a, H i

It is'desirable, hereforepotonly to protectther fi t e -ia e i s i in r t ls c' v vde' for reafiplicatiomof-the brakes; on the-wheels' followin gi an y s'lipping oonditionoi the wheels; to: a high degree so that there is no substantial penalty. in the wayoflengthening of stopping-distance.

It has accordingly been proposed to provideap paratus for automatically; sanding the rails in advance of the car wheels at the time a slipping condition of any"of"thewheels first occurs durirlgarly one bralke'applicatiori', for thepurpo'se of sD incFeaSing theadhe'sion between 1 thewheels and thewailsas to= enable-full reapplication' of" the bra-he's -onthe wheels without causing recur rent slipping cycle's cin=a wheelwhich first slipped and--without--cau'sin'g slipping of other 'wheels on the same car of the train.

It is an-object pfmyfiresent invention to provide -a' novT-combinedbrake andsanding control" apparatus; functioning; to relieve the "braking forces' 'associatewwith a slipping wheel so "as"to' prevent sliding ofthe wh'eel'and to-sirhultaneousli effect -sariding'- of the track-rails in advance of a group of car wheels "including the slipping wheel-r More'spe'cifical'lyf it ah=objectdfqny invention Such devices or appa'ratus- 5 5 to providwbrahe anwsahding 'controrapparatus" of the type indicated in the foregoing object, characterized by a novel arrangement including a vent valve mechanism so constructed as to reduce brake cylinder pressure in response to a wheel slip condition and at the same time to initiate sanding of the rails in advance of a group of car wheels including the slipping wheel.

It is another object of my invention to provide brake and sanding control apparatus, of the general type indicated in the foregoing objects, wherein the apparatus is partly mechanical and partly electrical in character.

It is another object of my invention to provide apparatus, of the general type indicated in the foregoing objects, wherein the apparatus is wholly mechanical in character.

The above objects, and other objects of my invention which will be made apparent hereinafter, are obtained in several embodiments of my invention subsequently to be described and shown in the accompanying drawings wherein Figure 1 is a simplified diagrammatic view, showing a fluid pressure brake and sanding control apparatus employing electrical sanding control apparatus for effecting sanding of the rails only while the slipping condition of the wheels endures.

Figure 2 is an enlarged sectional view of the vent valve mechanism shown in Figure 1, showing details of construction thereof,

Figure 3 is a simplified fragmental view of a different embodiment of my invention similar to that in Fig. 1 but characterized by the fact that a continuous sanding operation is initiated in response to the first slipping cycle during a given brake application.

Figure 4 is a simplified diagrammatic view, partly in section, showing another embodiment of my invention which is wholly mechanical in character and requires no electrical control apparatus as does the previous embodiment shown in Fig. 1 but which is the functional equivalent thereof,

Figure 5 is an enlarged view, partially in section, of the vent valve mechanism shown in Figure 4, showing pertinent details thereof, and

Figure 6 is a fragmental sectional view of the bleeder device shown in Figs. 4 and 5, showing a screw plug inserted therein for the purpose of modifying the sanding control characteristics provided by the arrangement shown in Figs. 4 and 5.

Figure 7 is a fragmental sectional view showing a modification of Fig. 6 employing a stop cock.

DESCRIPTION Figures 1 and 2 Referring to Figures 1 and 2 of the drawings, the embodiment of my invention shown therein comprises a fluid pressure brake control apparatus of the well-known straight-air type, although it will be understood that my invention is applicable to any type of fluid pressure brake control apparatus.

As shown in Figure 1, the apparatus comprises a brake cylinder I I operative through conventional brake levers and rigging, not shown, in response to the supply of fluid under pressure thereto to effect application of the brakes on the wheels I2 of a wheel truck; a straight-air or control pipe I3 which is charged with fluid under pressure to a degree corresponding to the degree of application of the brakes desired, as by suitable apparatus illustrated simply as a brake valve I4 of the well-known self-lapping type; a reservoir I5 normally charged with fluid at a certain uniform pressure by a fluid compressor not shown; and a vent valve mechanism Iii ar anged to control the supply of fluid under pressure from the control pipe I3 to the brake cylinder II and the automatic release of fluid under pressure from the brake cylinder II under the control of so-called Decelostats or wheelslip detecting devices I! of the rotary inertia type associated with the wheels I2.

The apparatus shown in Figure 1 further includes, according to my invention, sanding and sanding control apparatus comprising a plurality of sanding devices, hereinafter referred to simply as sanders I8, of well known construction effective upon the supply of fluid under pressure thereto to deliver sand to the rails immediately in advance of the vehicle wheels I2, a sanding reservoir I9, and an electro-magnetically operated control valve 20, hereinafter referred to simply as the sanding magnet valve, for controlling the supply of fluid under pressure to charge the sanding reservoir I9 and the supply of fluid under pressure from the sanding reservoir to the sanders I8. A suitable electro-magnetically operated counting device 2| may also be provided for registering the number of operations of the vent valve mechanism in response to the occurrence of wheel slip conditions.

Considering the parts of the apparatus in greater detail, self-lapping brake valve I4 is of the well-known type having a self-lapping valve mechanism including a rotary operating shaft to which an operating handle I la is attached. In the normal or brake release position of the brake valve handle I la, the self-lapping valve I4 vents fluid under pressure from the control pipe I3 through a branch pipe Ilia and an exhaust port and pipe 22 at the brake valve. When the brake valve handle I la is shifted out of its brake release position into its application zone, the self-lapping valve mechanism of the brake valve I4 is operated to cause fluid under pressure to be supplied from the reservoir I5 by way of pipes 23 and 24 and pipe I312. to the control pipe I3, the pressure in the control pipe being automatically limited to a pressure dependent upon the degree of displacement of the brake valve handle out of its brake release position into the application zone.

The control pipe I3 extends longitudinally of a car and is suitably attached to the body of the car, sections of the control pipe on successive cars being coupled through suitable hose couplings 25 in conventional manner to provide a so-called train pipe extending throughout the length of a train.

The brake cylinder II and the vent valve mechanism I 5 are carried on the spring-supported frame of the wheel truck. Fluid under pressure is supplied from the control pipe I3 to the brake cylinder by way of a flexible branch conduit or pipe 26, connecting the control pipe to the pipe bracket portion of the vent valve mechanism I6, and a pipe 2'! connecting the pipe bracket portion of the vent valve mechanism It to the pressure chamber of the brake cylinder I I. Pipe 21 may be either rigid or flexible as desired. As will hereinafter appear, the vent valve mechanism I6 is normally conditioned to establish a communication therethrough b e t W e e n the branch pipe 28 and the brake cylinder pipe 27 so that the brake cylinder II is charged to the same pressure as that established in the control swan;

pipe :i3.- The several "*Decelostats H are connected pneumatically to. the pipe 1 bracket portion oi-the vent valve mechanismrlfithrough a ilexia ble conduit orhpipelfifi having. corresponding branchessaa andltlb; v V

Theventvalvemechanism It is identical in to th vent valvemechanism disclosed and claimed Jinthe suspending application, Serial No. 523,d50 of Jose.ph.t..McCune, filed .Fehruaryfli,

1944 and assigned to the assigneeoi the present application and which was issued .Dec. 2.6,. 19,44 as Patent Number 2,365,044.. ,According. to my present invention, the. vent,- valve mechanism shown in the copending application of Joseph C, Mcflune just referred to is modified in a manner to function as lbflt'h a pneumatic cr-iluid pressure control valve device landas an electrical switch device. v e V .r

Referring to Figure 2, vent valve mechanism 4:5 comprises a pipe bracket-and mounting sec? :tion Ilia, .a valveor body section ;l3h,,a cap 59;:- tion 116C, and a switch casclsegesection 263d, The casing sections i601, it?) and lie are suitably secured together by screws, not ,shown,,with sealing gaskets interposed between the cooperating contact facesof the casingsections. The switch casing section 16d, which is in the form of atuhular member or sleeve, is adapted to be supported from the casing section Nib in manner hereinafter to be described,

The pipe bracketsection its has three ports .or passages 263cc, Zlm anddmc therein to which correspondingly numbered pipesor conduits 26, El, and 28, respectively are connected, Aport .29 in the body of the pipe bracket section connects the passage itrand the passage its: and is threaded to receivea screw type choke fitting .359 having a restricted orifice 31. The end opening of passage 26:0 at the inner face of the pipe bracketsection l is opposite the port .29 .so that choke ,fitti-ng may be inserted in the port through the end of the passage before attachment thereof to-casing section i 519,. The purpose of the choke-fitting 3.9 will heexplainedpres- ,ently. V V V The valve-section llfib'rhas a lower conical portion in which ;a largevent port 322 is provided which .is controlled by a differential piston valve Th differential piston valve comprises an annular piston 34 and landisctyne piston ,35 or" smaller diameter, the two pistons being connected Joya tubularstem .The outer face oithe piston 65 has an annular gasket (all 1 secured therein :for engaging an annular rib seat formed on aseat bushing -38 fixed, as by a press fit in a circular bore of the casing section lfibconstitutling vent port 32.

lllhelpiston 3d operates in-albushing ,t'flzflxed as by a press fit in a bore formed in thelcasing sec- I tion ,ifib. The piston operates in a similar bushing Ail of smallerdiameter also fixed as by a press lit in a bore formed in the casing, -in coaxialrelation-to the bushing 39.

.Thehushing ildextends through a chamber .tl having a port 40a to .whichthe passagelilxlinthe pipe bracket section Ilia isconnected. The interior of the'hushing it .Qpenslat the upper end thereof into achainlaer d2 having a port lid to vwhicht-he passage its in the pipebraoketsection tl-fija islconnected. v

A plurality of peripherally spaced qports A3 in th =bushing 49 provides communication between the chamberlfl nndrithe chamber It! when :the ,pistonr35c1f the piston valve 33 Eisseated ;onithe seatiibushing'tld It thus he apparent that when the control pipe lfiinFigure 1 ischarged with fluidlnnderpressure, such fluidrunder priessure fiswsthmugh the pipe 26, passage 2.6m and port 432a tochantber 42, where it acts on the low- .er face of the piston 34, and thence through the ports Min the bushing so tothe chamber 4!, and through the port dim, passage Zlmand pipe to the brake cylinder ll.

Eormedabove the annular piston 34 within the hashing it is av chamber 4 5. A passa e 282 nedinthelcap section ificconnects chamber tits acpassageitt in thecasins section 1611 that, in turn, is ncnnectedto the passage 2.80: in the pipe bracket section its. It will thus be Seen that when fluid under pressure is supplied to the-chamber dd beneath the annular piston 34, fluid under pressure is simultaneously supplied thrcf Fh the orifice iii in the choke Fitting so from the passage 26: to the passage i383), and thence through the passages t dy and 28s to the chamber above the pistonfl h .A coil-spring 45, contained in the tubular stem is interposed between the face of the cap seciticand the inner face of the piston 35 for I the piston into seated position on the seat bushing '38 in opposition to the fierce of the dpressure in chamber 62 exerted upwardly on lower ,face oi the-piston 3d. 7

when fiui-dunder pressure is vented from the pipe 2 3, as by operation of the one or more of the Decelostats it in the manner hereinafter to he described, at a. rapidrate faster than that at which fluid under pressure is supplied through thechoke orifice 3| to the passage 28s, a, difierial fluid pressure is built-up on the annular pistontit le-ffecti e to urge the piston 3d upwardly in opposition to the force of the spring &5, the piston ultimately seating on the contact face of the cap section we within the chamber it.

In such position of the piston valve 33, the piston 35 is in a position above the ports in. the bushing d0, thereby cutting on communication between the chamber 42 and the chamber 41 through which fluid under pressure may be supplied from the control pipe it to the hralte cylinder ii, i At ,the same time, with the piston 35 unseated from the seat bushing the chamber M :and'the connected brake cylinder ii are connected to atmosphere through the ports and the exhaust port .32 in the manner more fully descrihedhereinafter so that fluid under pressure is thusrapidly exhausted from the brake cylinder H.

In order to maintain the piston valve 33 in its uppermost position, in which fiuid under pressure is vented from the brake cylinder H, until the pressure in the brake cylinder reduces below a certain low pressure, such as eight pounds per square inch, the vent valve mechanism !6 is provided with an arrangement comprising a poppetvalve Miand a control valve 41. The poppet valve-45 seats on a seat bushing 48 fixed in a here 4.9 the cap section I60 and has a cylindrical guiding stem 5!) that is slidably received inia bore 51 in a screw plug 52 closing the open end of the bore 49. A coil spring 53, interposed between the screw plug 52 and the valve 4.6, yieldingly biases the valve into seated position onthe seat bushing 48.

Extending from the valve 48 on the side oppositethe'guide stem 50 is a fluted stem 54 that operates sli-dably in the bushing 48 and has a circular end portion erv extension that extends downwardly through the chamber 44 into the interior of the tubular stem 36 of the differential piston valve 33 in coaxial relation thereto. The lower end of the stem 54 extends into sufficient proximity to a boss 55 on the inner face of the piston 35 that when the piston 35 is raised to its uppermost position, the boss 55 engages the end of the stem 54 and unseats the valve 46 a certain amount.

The control valve 4! is contained in a chamber 56 that is connected through a passage 51 to the bore 49. If desired, a choke fitting 58 having a restricted orifice 59 may be disposed in the passage 51, as shown, for somewhat restricting the rate of flow of fluid under pressure through the passage under circumstances hereinafter described. The valve 4'! is normally seated downwardly on a seat bushing 60, as by a spring 6|, in opposition to a spring 62 which tends to unseat the valve. The spring 6| acts on the closed end of a sleeve type follower 63 that operates slidably in a bore 64 formed in a relatively large cap screw or screw plug 65 that is, in turn, screwed into a suitably threaded bore in the casing section I60, the follower engaging the upper face of an imperforate flexible diaphragm 66 of rubber or metallic composition secured in the casing section I60, as by clamping the periphery thereof by the screw plug 65. A protective washer 6'! may be interposed between the end of the screw plug 65 and the diaphragm 66 to prevent damage to the diaphragm in response to the tortional clamping action of the screw plug 65 when it is tightened home.

Surrounding the bore 66 and the follower 63 in the plug 65 is an annular chamber 68 which is open to the upper face of the diaphragm 66. Chamber 66 is also open to atmosphere through a passage 63 leading to an atmospheric port 16. Port 16 also connects the chamber at the back of the sleeve follower 63 to atmosphere to prevent dash-pot action thereof interfering with rapid unseating of valve 47.

Control valve 4? controls communication between chamber 56 and a passage 12 leading to the chamber 6|. The inner seated area of valve fill is thus subject to the fluid pressure in the chamber 4| and the connected brake cylinder When the poppet valve 46 is unseated upward-- ly by the piston valve 33, it causes the chamber id to be connected through the bore 49 and passage 5'1, including the choke orifice 59, to the chamber 56 at the lower side of the diaphragm 66. Assuming sufficient fluid pressure to be established in the brake cylinder H, as hereinafter described, the valve 4'! will have been unseated by the brake cylinder pressure acting on the inner seated area thereof in opposition to the force of the spring 6|. With the chamber 56 thus charged with fluid at the same pressure as that in the brake cylinder, the force of the spring 6| is nullified and spring 62 is effective to hold the valve 67 unseated upwardly from its seat bushing 66. With both valves 46 and valve 41 unseated simultaneously, the chamber 44 and the connected chamber 56 are connected past the unseated valve 41 and through passage 12 to the chamber at. The pressure of the fluid in the chamber 44 thus reduces substantially in accordance with the reduction of the pressure in the chamber 6| and the connected brake cylinder- II.

The piston valve 33 is maintained in its uppermost position by the pressure of the fluid in the chamber 42 beneath the piston 34 as long as the control valve 4'! is unseated. When the fluid pressure in the chamber 56, active on the lower face of the diaphragm 66 and corresponding to brake cylinder pressure, reduces to a low value such as eighteen pounds per square inch, the force exerted by the spring 6| becomes effective to reseat the valve 41. With the valve '3! reseated, the fluid under pressure supplied through the orifice 3| of the choke fitting 3U from the supply pipe 26 and connected passage 26.1: and through the passages 28x, 28y and 28a to the chamber 44 above the piston 34, promptly restores the fluid pressure in the chamber 44 to a value which, with the assisting force of the spring 45, is elfective to promptly shift the piston valve 33 downwardly to the position wherein the piston 35 is again seated on the seat bushing 38. A certain time interval elapses between t e instant that the valve 41 is reseated and the instant that the piston 35 cuts off the further venting of fluid under pressure from the brake cylinder due to the time required to build-up the pressure in the chamber 14 through the choke orifice 3| sufficiently to shift the piston valve 33 downwardly. During this time interval, the reduction of brake cylinder pressure continues, and at the time the piston 35 actually seats on the seat bushing 38 to cut off further reduction in brake cylinder pressure, the brake cylinder pressure will have reduced to a value such as eight pounds per square inch.

With the piston valve 33 restored to its normal position as just described, the spring 53 acts to reseat the poppet valve 46 by reason of the disengagement of the boss 55 on the piston from the end of the stem 45 of the valve 46. Spring 53 is of such strength as to maintain the valve 56 seated in opposition to the pressure of the fluid pressure built-up in the chamber 43 and acting on the inner seated area of the valve 46.

With the piston valve 33 restored to its normal position shown in Figure 2, the supply communication between the supply pipe 26 and the brake cylinder pipe 2'l is again established through the ports 43, and the pressure in the brake cylinder is thus again built-up in accordance with the pressure established in the control pipe I3.

Upon restoration of fluid pressure in the brake cylinder II, the valve l! is again unseated in response to the brake cylinder pressure active through the passage 72 on the inner seated area of the valve. Chamber 56 is thus again charged to a pressure corresponding to brake cylinder pressure and such pressure acts through the passage 51 and bore 49 on the outer face of the poppet valve 46 to assist spring 53 in maintaining it seated against the pressure of the fluid in the chamber 54'.

It will thus be seen that when the pressure of the fluid in the chamber 44 is suddenly reduced by operation of one or more of the Decelostats I! in the manner more fully described hereinafter, the pressure of the fluid in the brake cylinder is promptly and automatically first reduced to a predetermined low pressure and then restored to a pressure corresponding to that established in the control pipe 13.

According to my present invention, the vent valve mechanism l6 further includes a switch mechanism within the switch casing section lBd arranged to be operated in response to movement of the piston valve 33. To this end, a tubular switch support member '14 is provided having at its upper end a portion of reduced diameter provided with threads whereby the member 14 may be screwed into the threaded end of the vent port valve 35 from brake cylinder flows into the hollow interior of the tubular member 14.

As will be explained presently, the Switch casing section 16b is supported in concentric surrounding relation to the tubular member M. In order, therefore, to permit the escape offluid under pressure from brake cylinder I lpast valve 35 to atmosphere the tubular member His pro;- vided with a plurality of relatively large ports in the wall thereof and the casing section Hid has a plurality of vent ports 16 in spaced relation around the periphery thereof, preferably atthe lower end thereof as shown.

The lower end of the tubular member 34 has a bore therein of slightly larger diameter-than the bore immediately adjacent thereto, so as to form an annular shoulder 11 serving as a stop for a cylindrical member 18 of insulating ma-- terial that is inserted endwise into the bore from the lower end of the tubular member 14. Embedded in the member 18 in diametrically disposed relation are two terminal posts--19 and 88 respectively, which project radially outwardly through suitable openings in the wall of the tubular member M. Insulating washers 8| surrounding the terminal posts 19 and 88 may be provided in the openings in the tubular member M through which the terminal posts extend in order to insure insulation of the terminal posts from the wall of the tubular member. The terminal posts 19 and 80 are provided with tapped bores to receive screws 82 for securing wires thereto.

At the lower end of the insulating member 18 is an annular recess for receiving two arcua'te contact segments or members 83 and 84 of suitable metal or metallic alloy. The arcuate contact segment 83 is secured in place by a screw 85 that engages in a tapped bore 85 in the terminal post 19, thereby electrically connecting the segment 83 to the terminal post 19. Similarly, the arcuate contact segment 84' is secured in place by a screw 85 that engages in a tapped bore 81 inthe terminal post 88, thereby electrically connecting the segment 84 to the post 80,

The cylindrical member 18 is provided with a central bore 88 in coaxial relation to the tubular member 14 through which a metallic operating stem 89 extends. Stem 89 is secured at its upper end, as by a screw threaded connection, to ,a central point in the piston 35.

88 havinga screw threaded connection with the metallic portion of the stem.

The insulating tip 98 of the stem 89 is adapted to engage a metallic sphere or ball contact 9! that is contained in a cylindrical bore 92 of a cylindrical insulating member 93 secured in the bore at the lower end of the tubular member 14 immediately beneath and in contact with the member it. A coil spring 94 is interposed between the ball iii and the closed end of the insulating member $3 for urging the ball 9! upwardly toward the arcuate contact segments 83 and 84.-

is seated on the valve seat 38, the ball 9! is shit ed downwardly from the contact segments 83 and- 88 to interrupt the electrical connection there-..

The lower end of the stem 89 is provided with an insulating tip.

The length. of the stem 88' is such that when the piston 35.

- the inner circular contact edges of the contactsegments 83- and 84 are shaped to conform to the curvature of the: surface of theball.

.In. view of the characteristic-operation of the piston valve 33 in snap-action fashion; it'will be seen that the make and break of. connections between the arcuate contact segments 83 and 84 by the ball contact ill will correspondingly have a snap-action characteristic. The insulating tip an onthe operating stem 89 prevents possible grounding of the circuit through the casing of thevent valve mechanism l5, which grounding is undesirable. r

The insulating members 18 and. 93 are held in position by a threaded sleeve 95' that is screwed into the outer threaded'end of the bore at the lower portion of the tubular member M, the inner end of the sleeve 95 engaging an annular shoulder formed on the member 93.

The switch casing section Hid rests at its lower endon an annular member or washer 96 that is fitted. over the projecting threaded end. portion. of thesleeve 95 and is secured. in clamped relation against the lower end of the tubular member M by aninternally threaded. cap member 91 screwed over the outer threaded. end portion. of the sleeve 95. In order to insure the concentric relation of the casing section 16d with respect to the tubular member 14', a plurality oi peripherally spaced nibs 98 are provided on the washer 96. These nibs are formed as by makingtwo closely spaced. radial cuts inwardly from the outer periphery of the washer 96,. the portion of the washer between the two cuts being bent upwardly to form the centering nibs 98. As will be evident in Fig; 2, the nibs-.98 are circularly arranged and thereby hold the lower. end of the casing section id in a fixed position on the washer 98.

In order to prevent loosening and possible loss of the cap member 91,, a cotter pin 99 that eX- tends through the cap member Gland the sleeve 85, may be provided asshown. i

The upper end of the casing section IGd is flared outwardly and engages the conical outer surface at the bottom of the casing section Nib in close contact so. as to prevent the entrance of dirt or dust into the. interior of the casing section 16d.

Although not shown, an annular sealing gasket of conical contour may be interposed between the flared upper end of the casing sectionl-fid and the conical portion otthe casingsection lfibto may. possibly accumulate thereon, fluid under.

pressure is allowed to escape to :atmosphere successively through the bore 88- in the insulating member 18, a port I08 in the insulating member 93..at.the lower end of the bore 92, and a port Olin the cap member 91. The fluid under pressure escaping past. the ballcontact 9| also causes rotation thereof, thus causing different portionsof the ballto engage the contact segments 83 and 84 when engagement. of the ball and segments, is

11' effected and thereby distributing the wear uniformly to all portions of the surface of the ball contact.

The Decelostats I'I associated with the vehicle wheels I2 are of the type disclosed and claimed in the copending sole application, Serial No. 485,130, of Joseph C. McCune, filed April 30, 1943, and the copending joint application Serial No. 533,284, filed April 29, 1944, of Joseph C. McCune and George K. Newell, the present applicant, both of which applications are assigned to the assignee of this application.

Since reference may be had to the copending applications just referred to for details of construction of the Decelostats it is deemed unnecessary to give more than a brief description thereof in this application.

Essentially each of the Decelostats I'I comprises a fly-wheel or rotary inertia element suitably journaled for rotat on in a casing attachable to the end of the axle journal of a railway car truck in place of the usual end cover, and a driving connection between the fly-wheel and the end of the axle so arranged that whenever certain rate of deceleration or acceleration of the wheels I2 aflixed to the ax e occurs, as when the wheels slip, the corresponding rotational lead or lag of the fiy-wheel with respect to the axle is effective to cause unseating of a normal seated or closed pilot valve device I'Ia carried by the casing or a removable part of the casing attached to the axle journal.

The branches 28a and 28b of the conduit or pipe 28 connected to the pipe bracket portion of the vent valve mechanism I 6 are connected respectively to corresponding pilot valve devices Ila of different wheel and axle units. Thus, when either of the pilot valve devices I'Ia are unseated or opened in response to the occurrence of a slipping condition of the corresponding wheel and axle unit, fluid under pressure is rapidly vented past the pilot valve devices from the pipe 28 and the connected chamber 44 of the vent valve mechanism I6, thereby causing a rapid reduction of the pressure in chamber M and consequent operation thereof in the manner previously described.

The sanders I8 are of standard and well-known construction and a detailed description thereof is thus deemed unnecessary in the present application. Sufiice it to say. each one of the sanders I8 includes a hopper I 8a containing sand which is delivered through a delivery pipe I 03 to a point in advance of the corresponding vehicle wheel I 2 in response to the supply of fluid under pressure to the corresponding sander.

Only two sanders are shown in Figure 1, one for each of the two vehicle wheels I2 shown. It will be understood, however, that an additional sander is provided for each wheel of the wheel truck and fluid under pressure is supplied to operate such sanders under th s control of the common sanding magnet valve 20, as will be expla ned more full presently.

Fluid under pressure is supplied to operate the sanders I8 under the control of the sanding magnet valve 20 which is, in turn, under the control of the switch portion of the vent valve mechanism I6.

The sanding magnet valve 20 is of standard construction comprising essentially a valve I 04 that is normally biased to an upper seated position as by a spring I05 and is actuated to a lower seated position in response to energization of a magnet winding or solenoid I06. With the magnetwinding I06 deenergized and the valve I04 in its upper seated position, communication is established past the valve I 04 from the reservoir pipe 24 to the sanding reservoir I9, thereby causing the sanding reservoir to be charged with fluid at a pressure corresponding to that in t e reservoir I5.

When the magnet winding I06 is energized and valve I04 is shifted to its lower seated position, the supply communication to the sanding reservoir is cut off and communication is established from the sanding reservoir I9 to a delivery pipe I01. Delivery pipe l 0'! is connected by two branch pipes I08 to a pipe I09 connected to both of the sanders I8 for the wheels I2 on one side of the car truck and to a pipe II 0 connected to the sanders, not shown, for wheels on the other side of the car truck.

It will thus be apparent that when the magnet Winding I 06 of the sanding magnet valve 20 is energized, fluid under pressure is supplied from the sanding reservoir I9 to all of the sanders I8 for all wheels of the particular wheel truck.

The manner of energizing the magnet winding I06 of the sanding magnet valve 20 under the control of the switch portion of the vent valve mechanism I6 will be apparent in Figure 1. Briefly, a pair of bus wires III and H2 are provided which are connected respectively to the positive and negative terminals of a source of direct current, such as the usual storage battery II3 provided on passenger cars. The magnet winding I06 of the sanding magnet valve 20 is connected in series relation with the switch portion of the vent valve mechanism It across the,

battery bus wires III and H2. It will thus be seen when the piston valve 33 is actuated upwardly in response to the reduction of the pressure in the chamber 44 by operation of one or more of the pilot valve devices I'Ia of the Decelostats II, the switch portion of the vent valve mechanism is thereby operated to close the circuit for energizing the magnet winding I06.

It is desirable for purposes of test and scientific analysis to know the number of times that the vent valve mechanism I6 is operated over a given period of time or over a given travel distance of a train. For this purpose, the counting device 2|, of standard and well-known construction, is connected in parallel relation to the magnet winding I05 to the sanding magnet valve 20. Thus, each time that the piston Valve 33 is operated through a cycle, that is raised and lowered, the electro-responsive portion of the counter 2| is energized and deenergized successively, the register of the counter advancing one unit with each individual energization of the electroresponsive portion of the counter.

OPERATION The operation of the apparatus disclosed in Figures 1 and 2 should be apparent from the previous description. However, a brief summarization thereof may be helpful for further understanding of the operation as a whole. Let it be supposed that a train of cars equipped with the brake and sanding control apparatus shown in Figures 1 and 2 is traveling under power and that it is desired to effect an application of the brakes. The engineer on the locomotive of the train accordingly cuts oif the propulsion power in the usual manner and causes the control pipe I3 to be charged with fluid under pressure corresponding to the desired degree of applicaner previously describedand epplicatiori ct the brakes associated withtneyehidewheas I2 is" accordingly effected=. 4

As long as the wheels continue to roll-in the: normal fashionand de'celerate at a rate ccrre= spending-to the rate or retardatihri o f' the -train;-

nofurther variation ofthe re'ssure in the brake: cylinder H occurs exce t in response to variation of the pressure in the control pipe l3 under the control of the engineer, who may either "increase or decrease the pressure; as desired, t'ccorre spondingly increase ord'e'crea-se the degree of ap-' plication of the brakes on the'vehicle' wheels.

If, when the brakes are first applied orat any time during-a brake application; a wheel unit of a particular car truck,- taken as thatshown' in Figure- 1 begins to slip dueto excessive braking force relationto the adhesibn' b'etweerr the wheel's and the rails, pilot'- vawe device I la of the corresponding l 'e'celostat will operate so as to cause operation of the'vent valve mechanism' l6 tOCllfi off the supply offluid under pressurefrom the'control pipe I 3 to the brake cylinder of thecorresponding wheel truck and to vent fiu-id under ressure therefrom at" a rapid rate.

As previously described, theoperatioii of the switch portion of vent valve mechanism l6"incident'al to and simultaneous with the operation of the vent valve mechanism to vent fluid under pressure from the Brake cylinder ll causes energi'zation of the magnet winding [06- of the sanding magnet valve 2' 0 and of" the operation counter 21-. Fluid under ressure is accordingly supplied from the sanding" 'eservoir l9 to'the' sanders; l8 under the contr'o'r o'f thernaig" tvalv'e 20, thereby causingthe sanders to operate: to deliver sand in advance ot tne vehicle wheels [2 of the wheel trucl i having the slipping wheel or wheel unit at the sametimethat fiuid under pressure is being vented from the brake cylinder.

As previously described, the vent valve mechanism is is so constructed amfdesi gned that. once it is operated to'vent' nuid un'derpressure from! the bra'ke'cylih'der associated therewith, it

renia'rrs conditioned to" continue the reduction of pressure in the brakecyli ndento a certain low ressure as' igllt pound-s: pec'square i iich after which" it is automatically. restored to its normal condition wherein' the further reduction. of pressure in the brake cylinder is terminated and the communication through which" fluid under pressure issupplied 'from' the control pipe to" the brake cylinder is-reestablished:.-

The time requiredfor the pressure in thebra ke cylinder to reduce to eight pounds per square inch from the pressure usually established-in-the brake cylinderwill-ordinarilybe Of-su'ch length that the slipping wheels-will have previously been restored to a speed-corresponding to train speed and be again decelerating in accordanc-e with the rate of-retardation ofthe train bythe. time that the vent valve mechanism i6 is restored to its normal condition.- Thus when the vent valve. mechanism IBis" restoredto its normal condition, the pilot valve device l'lci of the Dec-el'ostat associated with the wheels which just slipped will have been ls'iit'd SC) as to" terminate the exhaust or fluid under pressure from the pipe 28 and 'thej chamber 44" of the vent" valve mechanism [6. Flu'id under pressure: coirresponding to" that" established in the control pipe I3 Will thus be restored in the brake cylinder H so that the brakes. on'the wheel truck having the slipping wheel unit or wheels will again be reapplied in accordance with the pressure of the fluid in the control pipe [3.

If the so-called bad rail condition or condition of poor adhesionbetween the wheels and the rails:: is a continuing one, it is likely that the reapplication of the brakes on the wheels of the truck having the wheels which just slipped will again cause those; wheels to begin to slip unless the adhesion between the wheels and the rails is improved in the interim.

In this embodiment of my invention, the sanding ofthe rails is discontinued automatically in response to the restoration of th vent valve mechanism 58 to its normal condition by reason of therdeenergization' of the magnet winding. I06 oi the sanding magnet valve 29 in response to the restoration of the switch portion of the vent valve mechanism to its open position. In this embodiment of my. invention, therefore, sanding of the rails is effected" substantially only during the timeinterval during which actual slipping of the wheels occurs. The advantage of the rail '5: sanding in this embodiment of my invention lies in the fact that the adhesion between the wheels and the rails is greatly improved by sanding during the slipping cycle of the wheels, thereby tending to insure prompt restoration of the slippingwhe'els to" a speed corresponding to vehicle speed.

If following automatic restoration of fluid pressure in the brake cylinder H, the? same or other wheels on which the brakes are applied by the brake cylinder begins to' slip, the above ona contror pressure remains: in the control pipe this is so because the: vent valve mechanism l 6 is always restored to its normal condition auto matically foil-owing:v operation thereof under the control of the Decelos'tat pilot valve devices Ila. Inic'ntd'er to: release: the brakes prior to again starting th'e train, the engineer reduces thepressure the'Ccon'trol' pipe l3= to: atmospheric pressure; as by 'operation'ofthe brake valve I' l. Fluid under pressure is accordingly released from the brake? cylinder I I by reverse flow from the brake cylinder to the control pipe and thence to atmo' sphere through the exhaust. port 22' at the brake valve.

The d'een'er'g'izaticin or the" magnet winding l st of 'asanding magnet valve 26' inres'pons'e to each restoration or the vent valve mechanism" it to its" norms-1 condition automatically causes recharging: of the sanding reservoir t9; thus providihg a constafitly' available source of fluid und'er' pressurefo r operating the san'ders' I 3.

Figure 3' Referring to Fig-ure- 3,v a brake and sanding shown in sisidenticartc thatinFigure 1:.

The cerrespondsng elements the two embodi- 15 ments are accordingly identified by the same reference numerals without further description. Only so much of the embodiment in Figure 3 as differs from the embodiment of Figure 1 will ac" cordingly be described.

Essentially the embodiment shown in Figure 3 differs from that in Figure 1 by providing a pressure operated switch I I5 and a two-winding electrical relay H6.

The pressure operated switch H5 may be of any suitable well-known type responsive to variations of under pressure supplied thereto with respect to a certain critical pressure. As employed the embodiment shown in Figure 3, the pressure operated switch H5 is connected through a branch pips itib to the control pipe I3 and is responsive to variations of pressure therein. It is so designed and constructed as to be operated to closed position whenever the pressure in the control pipe increases above a certain low pressure, such as five pounds per square inch, and to be restored to its open po ition whenever the pressure in the control pipe reduces below five pounds per square inch. In effect, therefore, the pressure operated switch 5 i 5 is closed whenever the brakes are applied and opened whenever the brakes are released.

The relay I I6 is a standard relay having a single contact and two windings Iiiia and H629 respectively. The contact of the relay is in its open position so long as both windings of the relay are deenergized. When-ever either of the windings I Ilia or IIEb of the relay is energized, the relay contact is actuated to its closed position or maintained therein if already in its closed position. As employed in this arrangement winding I Ifia functions only as a pick-up winding whereas winding I Ifib functions as a holding winding.

The winding IIIia of the relay He is connected in parallel relation with the electroresponsive element of operation counter 2!, both being in turn in connected series relation with the switch portion of the vent valve mechanism I6 across the bus wires III and H2.

Upon closure of the switch portion of the vent valve mechanism I6, the electroresponsive element of the operation counter 2| and winding I Ifia of the relay IIIS are therefore simultaneously energized.

The contact of the relay H6 is a self-holding contact which is effective in its picked-up or closed position to establish a self-holding circuit for the winding IIISb of the relay H6 and also a circuit for energizing the magnet winding I86 of the sanding magnet valve 20 and maintaining it energized under the control of the pressure operated switch I I 5 independently of the switch portion of the vent valve mechanism I 5. This holding circuit may be traced from the bus wire III by way of a wire IN, the switch contacts of the pressure operated switch II5, a wire H8, and the contact of relay contact I I6 to a wire I I9, whence the circuit continues in parallel through the magnet winding I05 of the sanding magnet valve 259 and the holding winding I Ilib of the relay I It to the battery bus wire IIZ.

It will thus be apparent that after the initial energization of the pick-up winding Ilsa of the relay I IS in response to closure of the switch portion of the vent valve mechanism It, the magnet winding of the sanding magnet valve 20 is energized and remains energized thereafter subject to the opening of the switch contacts of the pressure switch H5 in response to the release of the brakes, notwithstanding subsequent deenergization of the pick-up winding I IBa of relay IIG. Thus, the sanding of the rails which is initiated in response to the occurrence of the first slipping condition of the wheels during any given brake application is continued thereafter during such brake application so long as sufiicient fluid pressure remains in the sanding reservoir I9, or until the brakes are released by the engineer and the switch contacts of the pressure switch II5 thereby restored to their open position, whichever occurs sooner.

In the embodiment shown in Figure 3, the electro-resp-onsive element of the operation counter 2i and the pickup winding I Ifia of relay are solely under the control of the switch portion of the vent valve mechanism I6 and are therefore deenergized whenever the switch contacts of the switch portion of vent valve mechanism I6 are restored to open position at the termination of a brake cylinder pressure reduction resulting from a wheel slip condition. The counter 2I thus registers each operation of the vent valve mechanism as in the embodiment of Fig. 1. Repeated energizations of the winding I I6a of relay H3 separated by intervals of deenergization in response to repeated operations of the switch portion of the vent valve mechanism I6 during any given application is without effect due to the concurrently established holding circuit for winding Hill) of relay IIS subject to the control of the pressure operated switch I I5.

The advantage of the arrangement shown in Figure 3 over that shown in Figure 1 lies in the fact that the continued sanding of the rails following the initial occurrence of a wheel slip condition reduces the possibility of recurrent or repeated wheel slip cycles of the same wheels or other wheels by reason of the improvement in the adhesion between the wheels and the rails produced b sanding of the rails.

Figures 4 and 5 Referring to Figures 4 and 5, another embodiment of my invention is disclosed which is entirely mechanical in character, that is, it does not employ any electrical or electroresponsive control apparatus. Insofar as the ultimate result is concerned, however, the embodiment shown in these figures is the functional equivalent of the apparatus or embodiment shown in Figure 1 except for the omission of operation counter 2|.

To a large extent the apparatus disclosed in Figures 4 and 5 is the same as that disclosed in Figure 1, corresponding parts in these two embodiments being therefore designated by the same reference numerals without further description. Only so much of the embodiment shown in Figure 4 as differs from that in Figure 1 need, therefore, be described.

Essentially the embodiment shown in Figures 4 and 5 differs from that shown in Figure 1 in providing a modified form of vent valve mechanism ISA, a fluid pressure operated sanding control valve 20A and a pipe-T I25, sometimes referred to hereinafter as a bleeder device I25.

As shown in Figure 5, the vent valve mechanism ItA differs from the vent valve mechanism I6 in having a pipe bracket and mounting section I6Aa different from that of the vent valve mechanism I I3 and in omitting the switch mechanism embodied in the switch casing section id of the vent valve mechanism I6. The valve body casing section ISA?) and cap section IBAc of vent valve mechanism I6 are identical to the valve body section I6band cap section- I'ii'c' of the vent valve mechanism I: In viewof the detailed description of the valve bodycasing 'section l-Bb and cap section I50 and parts thereof in" connection with FigureZ above, the detailsof the valve body section IB'Ab an'd cap s'ection I IiAc of the vent valve mechanism: I'GA are not shown in Figure 5, except in outline:forin arid will ndt'- be further'describe'd;

Insofar asthe'pipe b-racket section I fiAa of the vent valve'mech'anism WA is concerned; it dif fers essentially from the pipe-braclcetsection Ifi'a of vent valve mechanism- [5 in that it is en larged or extended somewhat to" accommodate and embody'a fiuid pressure operated Valve de Vice comprising a valve I30 o'f the=poppefi t'y-pe secured t'othe central point in a-ciroular-fie'xible diaphragm I 3 I that is -controlledaccording tit the differential of fluid pressure inthe' passages: 25x and28w.

The valve I39 and the} diaphragm IBI are: inserte'd, preferably as a unit, in a threaded bore I32 that intersects the passage ZB'randa counterbore I33 of smaller diameter'that intersects the passage 26st. The diaphragm is received in an annular recess IN andis clamped ih position along theperiphery' thereof-by a screw plug I35 with an annular member I35 intervening there'- between'. The annular member I 36- has' a plurality of peripherally spaced radiallyextending ports or openings I31 therein to maintain the continuity of thepassage I Q-Iiwwithout substantial restriction to flow of fluidunder pressure therethrough.

The screw plug I35 l'1asa hollowinterior and a centrally disposed stop pin I38- is formed thereon, the end ofwhich serves as a stop to be engaged by a follower I39 associated with the diaphragm IS'I to limit the upWard-flexingof. the diaphragm Isl to a safe degree. A coilspring let, interposed between the screw plug. and the follower I39 in surrounding relation t'oth'e stop pin I38, normally yi'eldingly urges the flexible diaphragm I3I downwardly so as to effect seating of the valve I3Il'on an associatedvalve! seat formed in thecasing".

The valve I353 controls the connectionbetween the passage 25m and a branch passage and port II, to which a' pipe I42 is-connected-that' le'ads to the sanding control valve 20A, the bleeder device I25 beinginterposed in "the pipe 2,;-

The pipe-T orb leeder device I 25- is'a sim'p-le fitting having a communicating: passage to the opposite ends ofwhich'the sever-a1 sections of the pipe Hi2 are connected and out of which a por-t threaded to receive a screw type choke fitting I43 opens. The outerend-oi the port receiving the choke fitting I43 is of: somewhat largerdiameter and is threaded to receive a' -screw plug M 1, as shown in Figure 6,.for a purpose hereinafter to be explained.

The sanding control valve 211A comprises a. suitable casing. containing a-pai'r of oppositely seating valves I55 and IE5 of the poppet type and a piston ll-for operatingthe valves in response to the supply offluid under pressure to and the release of fluid under pressure rom a chamber [that one slde'of the piston. mum? der pressure is suppliedto' and'releasedfromthe chamber l' l iithrough-the pipe l4'2 which is" connected to a suitable passage" tem the casingof the sanding control valve that opens into the chamber I68.

The-valves I45 and I46 are contained in a chamber I5fl to whiohthe'sanding reservoir I9 is connected as'by a pipe I51 and-passage I52; The valve i tr5'has afluted stem guided in a suitable port or passage and extending into a chamber I53 that is connected by a passage I54 and two pipes I55 to the pipes I09 and I Ill leading to the sanders 18.

The valve N15 has afluted stem suitably guided in t-he casing and" extending into a chamber I55 to -which fluid under pressure is supplied from the reservoir I5 through the-pipe 24 and a suitable-air strainer or cleaner I51 embodied in the sanding control valve-casing.

Acoil spring I58; interposed between the end of the stemsotthe valve I46and the casing within the chamber I56, normally urges the valves I45 and I46 upwardly to seated and unseated positions respectively. Fluid under pressure is accordingly supplied from the reservoir I5- by way of the pipe 24, air cleaner I51 and chamber I58 pastthe valve MB to the chamber I and the connected sanding. reservoir I9 to charge the sanding reservoir.

Upon the supply of fluid under pressure to the chamber M8" above-the piston M1, a resilient contact stem or button I59 in the stem Ifiilof the piston engages the end of the fluted stem of the-valve- IE5 and act'uates the valves I45 and Hit simultaneously to unseated and seated positions respectively. With the valve HIS seated, the supply oflfiuid'un'der pressure to charge: the sanding reservoir I9" is cut offl At the same time, with the valve" I IEunseated, communication is establishedpast the valve Hi5 through which fluid under pressure flows from the sanding reservoir I9 through the pipe I51, passage I52, chamber let; chamherj I53, passage I54; and pipes 15am thesanderpipes' I59 and H30.

Whenever the pressure in thechamber I48 reduces" sutficientlyto enable the'spring I58 tores'tore the valves I45"- and I'4'8 upwardly to seated and}unseated pcsitions'respectively, the supply of fluid underpres'sure' from the sanding reservoir 1 9 to the sandersIIi is cut ofi' and the charging communication through which fluid under pressure" flows" from the "reservoir I5 to the" sanding reservoiris again established; I

(ionsidering; the operation of" the embodiment shown in Figure 4 as a whole, the engineer may efiectapplication and release of the brakes by controlling the pressure in the control pipe- I3 in exactly the same manner previously described in connection with" Figure 1, fluid under pressure f-lowingef-rom-the control pipe- I-3 to the brake cylinder H and returning reve-rsely from the brake cylinder to the control pipe, as previously described-in connection with Figure l,-by way of the vent valve mechanism ISA. v

So long-l as aslipping condition of l the vehicle wheels does not-occur, the valve [3% in the pipe bracket section ofthe vent valve mechanism IGA remains seated due to the fact that the fluid under pressure supplied from the control pipe It byway of thepipe 2'6 and-passage 25 a: and'acting on the lower faceof thediaphragm I3! flows through; the orifice 31 of the choke-fitting 3| to the passage 2'83: and the upper face of the'diaphragm I3I- at such a rate that a differential fluid pressure" is not created onthe diaphragm sufficient to'ov'erco'me' the force of the spring I ia ma ntaining valve Ian I seated.

If a Wheel slip condition occurs',. however;. and one or'more o'fthepilot valve devices Ila of the Decelostats" I'I operate to vent fluid under pressure to atmosphere from the pilot valve pipe 28, a fluid pressure differential force is created on the diaphragm I3I sufiiciently efiective to urge the diaphragm upwardly to a position in which the follower I39 on the diaphragm engages the end of the stop pin I38 and in which the valve I30 is unseated.

Thus, while the mechanism in the valve body section ISA-b of the vent valve mechanism I6A is operating in the manner previously described in connection with Figs. 1 and 2, to cause fluid under pressure to be exhausted from the brake cylinder II by way of the brake cylinder pipe 21 and passage 21:0, fluid under pressure is being supplied from the passage 26x past the valve I30 through the passage I 4| and through-the pipe I-42 to chamber I48 of the sanding control valve 20A.

Assuming that the screw plug I44 is not inserted in the port of the bleeder device I 25, fluid under pressure will escape at a restricted rate through the orifice of the choke fitting I43 but the rate of exhaust or bleed is less than the rate of supply to the chamber I 48 so that the pressure in the chamber I 48 builds-up substantially to the pressure of the fluid supplied from the pipe 26 and connected control pipe I3.

Due to the fact that fluid under pressure escapes from the pipe '28 and passage 28:1: either past the operated pilot valve device I'Ia of one or more Decelostats or by way of the exhaust port 32 of the vent valve mechanism I6A at a faster rate than the rate of supply through the choke orifice 3| of choke fitting 30, a sufficient differential fluid pressure will remain effective on the diaphragm I3I to maintain the valve I30 unseated until the valve mechanism IBA is operated in response to the reduction of brake cylinder pressure to eight pounds per square inch, to its normal position restoring the communication through which fluid under pressure is supplied from the pipe 26 to the brake cylinder pipe 21. At such time the rate of supply of fluid under pressure through the orifice 3I of the choke fitting 30 is sufliciently rapid to cause prompt equalization of the pressure in the passages 28m and 28x, thereby rendering the spring I40 effective to urge the diaphragm I3I downwardly to reseat the valve I30.

It will be understood that so long as the valve I30 is unseated, and fluid under pressure continues to be supplied from the pipe 26 and passage 26a: to the chamber I48 of the sanding control valve 20A, fluid under pressure will continue to be supplied from the sanding reservoir I9 to the sanders I8 to cause sanding of the rails in advance of the wheels of the corresponding wheel truck. When the valve I30 is reseated, the pressure in the chamber I48 is promptly and sufficiently reduced through the orifice of the choke fitting I43 in the bleeder device I25 as to cause a prompt termination of the supply of fluid under pressure from the sanding reservoir to the sanders and a reestablishment of the communication through which fluid under pressure is supplied from the reservoir I to recharge the sanding reservoir.

Functionally, therefore, the embodiment shown in Figures 4 and 5 is substantially the equivalent of that shown in Figure l for the reason that sanding of the rails occur substantially only during'the time of occurrence of a'wheel slip condition.

Figure 6 If the screw plug I44 is inserted in the exhaust port of the bleeder device I 25, as shown in Fig. 6, the reseating of the valve I30 of the vent valve mechanism I6A is ineflective to cause termination of the sanding of the rails for the reason that the pressure of the fluid supplied to the chamber I48 remains trapped therein and cannot escape through the bleeder device I25.

It will thus be seen that when the screw plug I44 is employed in the bleeder device I25 sanding of the rails is initiated on the occurrence of the first slip of Wheels on the corresponding truck and such sanding continues thereafter, notwithstanding reseating of valve I30, until the pressure in the sanding reservoir I9 is depleted, or until the brakes are released by the engineer, whichever occurs sooner. In this respect the embodiment represented by Figure 6 is functionally similar to that of Figure 3.

If the brakes are released by the engineer before the sanding reservoir I9 is depleted, it will be apparent that the reduction of the pressure in the control pipe I3 and the consequent reduction of the pressure in the pipe 26 and passage 26:1: will cause a corresponding reduction of the pressure in the passage 28:0. The pressures on the upper and lower faces of the diaphragm I3I will thus be promptly reduced to atmospheric pressure. Consequently, when the force of the fluid pressure trapped in the chamber I48 and in the pipe 42 and passage I4I acting on the inner seated area of the valve I30 is suiflcient to over- F come the resisting force of the spring I 40, the

valve I30 will be unseated and the pressure trapped in the chamber I48 will be reduced substantially in accordance with the reduction of the pressure in the control pipe I3. Due to the relatively low force of the spring I 40, a small amount of fluid under pressure may remain trapped in the chamber I48 when the screw plug I44 is employed. However, such remanence of fluid under pressure in the chamber I48 will be ineffective to prevent the restoration of the sanding control valve to its normal condition shown in Figure 4, wherein the sanding reservoir is recharged.

Figure 7 Referring to Figure 7, a modification of the arrangement shown in Figure 6 with respect to the bleeder device I25 is shown wherein a bleed choke I43a, corresponding to the bleed choke I43, is rendered effective or ineffective under the control of a stop cook or other suitable manually operated valve I45 instead by the screw plug I44.

In this arrangement, the stop cock body has a threaded projection which screws into the threaded opening of the pipe-T I25, the exhaust passage I46 in the stop cock being connected at its inner end to the passage in pipe-T I25 connecting the several sections of the pipe I42. For convenience, the choke MM is screwed into the outer threaded end of the passage I48.

With the operating handle I 41 the tapered valve element I48 of stop cock I45 in the position shown, the port I49 in the valve element opens passage I48, thereby permitting fluid under pressure to be vented from the chamber I48 of the sanding control valve 20A to atmosphere through the orifice of the choke I43a.

When the handle I41 of the stop cock I45 is turned to a different position, the valve element MB closes. passage: I46; thereby preventing the bleeding: of fluid under pressure from thachame ber' I48 through the choke l-43a.

Functionally, therefore, the arrangement shown: in Figure-'7 is the equivalent of that shown in Figure 6.. In. order to prevent undesired or malicious tampering, the handle 141. of the stop cockispreferabl y removed afterthe valve element is set in any particular position. Operation of the stop cock onlyby authorized person isthus assured.

Having regard totheforegoing disclosure, thepatent of whichthis specification for-ms par-t confers, subject tothe conditions prescribedin The Patent Act, 1935, the exclusive right, privilege and liberty of making, constructing, using and vending to others tobeused'; the inventionas defined in claims submitted by the patentee as follows:

1 In a vchiclebrakeand sandingcontrol apparatus, the combination of a valvemeclianism having avalveelement operative in respon'se'to a predetermined variation of a control fluidpressure from one position in which it establishes communication through which fluid under pressure may be supplied toeffect application oi'the brakes to adifierent position in which the sup ply of fluid under pressure to effect application of the brakes is cut off and a different communication isestablished through which fluid under pressure is vented to effect a reduction in the degree of application of the brakesassociated withoneor more wheels of the vehicle, means responsive to-theslipping condition of a vehicle Wheel on which thebrakesare applied for ef footing thepredetermined variation of the controlfluid pressure'for the said valve element, and control meansincluding an operatingelement connectedto and operated by movement i of said valve element-for efiecting a sanding-operation in response to movement of the valve element to its said different: position.

2. In a vehicle. brake and sanding control apparatus, the combination of aivalve mechanism having. a: valve. element operative .il'll response to a predetermined variation of a control fluid pressure from one position in which it establishes communication through whichzfluid under pres sure may be supplied to efiect application ofthe brakes: to a. different positionin which the supply of fluid under pressure to effect application of the brakes is cutoff and a diiferent communication is established through which fluid under pressure is vented to effect a reduction in the degree of application of the brakes associated with oneor more wheels of the vehicle, means responsive to: the slipping condition of'a vehicle wheel on which the brakes are applied for effecting the predetermined variation ,ofithe control fluid pressure for the said valve element, switch means actuated by movement of said valve element, and electroresponsive means controlled by said switch means for controlling a sanding operation.

3. In a vehicle brake and sanding control apparat'us, the combination of a valve mechanism" normally conditioned to establish communica tion' through which fluid under pressure may be supplied to" effect application of the brakes as'' sociated with'awheel'oi thevehicle and'opera'tive tocut offthesupplyoifluid under pressure to" efiect application ofthe' brakes and establish anexhaust communication through *which fluid under pressur'e is released to effect a reduction m the vehicle to a* certain low degree" and thento the degree ofapplication of the b-ralies associated with the-said wheel; means operativelw resp'on sivetoa slipping condition: of the said' wh'eel for effecting operation of said valve mechanism, and means mechanically operated by operation of said valve mechanism for causing a sanding operation simultaneously with reduction in the degreeof application of the brakes.

i; In a brake and sanding' control apparatus; the combination of means responsive to t-he' slipping condition of a wheelof the vehicle, valve mechanism controlled by said wheel slip re sponsive means and operative upon the oc'cur= rence of a slipping condition of" said wheel to effect a reduction in thedegree or application ofthe brakes associated with" the said' wheel to a certaindegree and thereafter to causereapplication of the brakes onsaid wheel to a degree higher than said certain" degree, andmeans controlled by said valve mechanism for effecting asanding operation substantially for such time only as said valve mechanism is operative to effeet a reduction in the degree of application of the brakes.

5. In a vehiclebra'keand sanding control apparatus, the combination offvalve mechanism including a fluid pressure operated valve element normally in a position establi hing communication through which fluid under pressure may be supplied to effect application of the brakes on a wheel of the vehicle and operative in response to a predetermined reduction" of a control fluid pressure acting thereon to' apo'sition cutting, off the supply of fluid under pressure to cause application of the brakes and establishing a difierent' communication through which fluid under pressure is released to effect reduction inthe degree of application of the brakes, means responsive to the slipping condition of the said: wheel of the vehicle for effecting, said predetermined reduction of the control fluid pressure active on said valve elementswitchmeans actuated by movement of said valve element to its different position to initiate a sanding operat'ion, and means rendered effective, upon operation of the switch mechanism to initiate asanding operation for causing the sanding operation to be continued thereafter independently of: the position ofsaidval ve element.

6. In a vehicle brake and sanding control apparatus, the combination of a valve device oper-- ative upon a predetermined reduction-of a'control fluidpressure to-effect reduction in the degree of application of the brakes active on a wheel of the vehicle toa certainvlow degree" and. then to restore the degreeofapplicationor the brakes to a higher degree, means responsive to a slipping condition of the said-vehicle wheelon:

which the brakes are applied for eiiectingsaid predetermined reduction of the control fluid? pressure for said valve device, a switch" device operative in response to-operation" of saidlvalve deviceto cause reduction inthe degree of theLapplication of the brakes for initiating a sanding paratus, the combination of a valvedeviceopera tive upon a predetermined reduc'tion of a controlfluid pr-essure to sheet reduction in the degree: ofapplication of the brakes active on a wheel ofrestore the degree of application of the brakes to a higher degree, means responsive to a slipping condition of the said vehicle wheel on which the brakes are applied for effecting said predetermined reduction of the control fluid pressure for said valve device, a switch device operative in response to operation of said valve device, and electroresponsive means controlled by said switch device in a manner to initiate a sanding operation in response to operation of said valve device to initiate a reduction in the degree of application of the brakes and to terminate the sanding operation in response to operation of said valve device to increase the degree of application of the brakes following reduction thereof.

8. In a vehicle brake and sanding control apparatus, the combination of a valve device operatively responsive to a predetermined reduction of a control fluid pressure for cutting ofi the supply of fluid under pressure through a communication normally established thereby through which fluid under pressure may be supplied to eifect application of the brakes associated with a wheel of the vehicle and to establish a different communication through which fluid under pressure is released to efiect reduction in the degree of application of the brakes associated with said Wheel of the vehicle, means operative in response to the reduction in the degree of application of the brakes to a certain degree for causing restoration of said valve device to its normal position, a switch device operatively controlled by said valve device, electroresponsive means controlled by said switch device for initiating a sanding operation in response to operation of the valve device to initiate a reduction in the degree of application of the brakes, and means rendered effective in response to the initiation of a sanding operation to cause it to be continued thereafter notwithstanding the restoration of said valve device to its normal position.

9. In a vehicle brake and sanding control apparatus, the combination of sanding means, a sanding reservoir, valve means normally conditioned to effect the charging of said sanding reservoir and operative to cut oil the charging communication for said sanding reservoir and to establish a communication through which fluid under pressure is supplied from the sanding reservoir to the sanding means to effect a sanding operation, fluid pressure operated means responsive to a predetermined reduction of a control fluid pressure for efiecting operation of said valve means, and means controlling said valve means in a manner to cause it to continue to cause fluid under pressure to be supplied from the sanding reservoir to the sanding means notwithstanding operation of said fluid pressure operated means tending to cause operation of said valve means to terminate the further supply oi fluid under pressure from said sanding reservoir to said sanding means.

10. In a vehicle sanding control apparatus, the combination of sanding means, a sanding reservoir, electro-responsive valve means normally conditioned to establish communication through which fluid under pressure is supplied to charge said sanding reservoir and operative upon energization to a difierent position to cut off said charging communication and establish a communication through which fluid under pressure is supplied from the sanding reservoir to the sanding means to efiect a sanding operation, an electrical relay having two windings, switch means operative substantially only while a Wheel of the vehicle is in a slipping condition to cause energization of one of said windings of said relay, said relay being operative in response to energization of said one winding to cause energization of said electroresponsive valve means to cause the supply of fluid under pressure from said sanding reservoir to the sanding means, and means responsive to the operation of the relay to cause energization of said electroresponsive valve means for eflecting energization of the other winding of said relay to thereby maintain said relay effective to cause continued energization of said electroresponsive valve means and the consequent continued supply of fluid under pressure from said sanding reservoir to said sanding means notwithstanding deenergization of the said one winding of said relay.

11. In a vehicle brake and sanding control apparatus of the type having a control pipe chargeable with fluid at a pressure according to the degree of desired application of the brakes associated with the wheels of the vehicle, the combination of a valve device normally conditioned to establish communication through which fluid under pressure may be supplied from said control pipe to eflect application of the brakes on a wheel of the vehicle and operative in response to a predetermined reduction of a control fluid pressure while the brakes are applied on said wheel to a difierent position in which the supply of fluid under pressure to effect application of the brakes is cut off and a different communication is established through which fluid under pressure is released to efiect reduction in the degree of application of the brakes on said wheel, means operative in response to a slipping condition of said wheel for efiecting said predetermined reduction of said control fluid pressure, switch means operative in response to operation of said valve device, electroresponsive means controlled by said switch means for initiating a sanding operation whenever the valve device is operated to initiate a reduction in the degree of application of the brakes, and means rendered effective in response to energization of the electroresponsive means for continuing energization thereof independently of the switch device and only so long as the fluid in the said control pipe is maintained above a certain pressure.

12. In a vehicle brake and sanding control apparatus, the combination of a valve device normally conditioned to establish communication through which fluid under pressure may be supplied to efiect application of the brakes associated with a wheel of the vehicle and operative in response to a predetermined reduction of a control fluid pressure acting thereon to cut off said supply of fluid under pressure and establish a different communication through which fluid under pressure is released to efiect a reduction in the degree of application of the brakes associated with said wheel of the vehicle, a sanding control valve device operative in response to the supply of fluid under pressure thereto to cause fluid under pressure to be supplied to effect a sanding operation, a fluid pressure operated valve operatively responsive to the predetermined reduction of control fluid pressure acting on said valve device to establish a communication through which fluid under pressure is supplied to the sanding control valve device, and means responsive to the slipping condition of said wheel for efiecting said predetermined reduction of the control fluid pressure acting on said valve device.

'13. 'In a-vehicle brake and sanding rcontro'l ap paratus, a :fluid pressure operated valve device normally conditioned to establish:communication through which fluid under pressure may be supplied to v effect application of the brakes associated with a wheel of the vehicleand operative 'in response to a predetermined :reduction of a scontrol fluid :pressure acting zthereon to a different position cutting oif the communication through which 'fiuid under pressure is "supplied to effect application of the sbrakes and establishing a different communication through which' fiuid'under pressure is released to effect a reduction in the degree of application of the brakes associated with :said wheel :of thezvehicle, a fluid-pressure operated valve subject to the "control fluid pressure acting on said fluid pressure operated valve device and :operative in response to vsaid predeterminedreduction of the 'COIltI'Ollfi'llld pressure acting on "said fluid-pressure operated valve device to cause fluid under pressure to be supplied to effect a sanding operation, and means for effecting said predetermined reduction of the control fluid pressure acting on said valve device andsaid'valve.

14. In a vehicle brake andsanding control apparatus, :the combination of means .responsive to the slipping condition f a 'wheel of the vehicle, valve means controlled by the wheel slip responsive means and effective upon the occurrence of a slipping condition of the said wheel to cause a reduction in the degree of application of the brakes to ascertain low degree and thereafter to cause restoration in the degree of application of the brakes to a higherdegree, and a valve device operative upon the occurrence of a slipping condition of the said wheel controlled by saidwheel slip responsive means and to cause fluid under pressure to be supplied to causeasandingoperation, said valve means and said valve device co-- operating in such manner that said valve means is effective to so control said valve device as to cause it to continue to causeifluid under pressure to besuppliedto cause the sanding'operation until such time as said valve means is' operated to restore the .degree of applicationoi the brakes to a higher degree.

15. In a vehicle brake and sanding controlap paratus, the combination of means responsive to the slipping condition of a Wheel of the vehicle occurring while the brakes are applied thereon, valve means controlled by said wheel slip responsive means and operative upon the occurrence of the slipping condition to efiect reduction in the degree of application of the brakes acting on said wheel to a certain'low degree and thereafter to "restore the degree of application to a higher degree, a valve device controlled'by said wheel slip responsive means and operative in response to the initiation of the slipping condition to cause fluid under pressure to be supplied to cause a sanding operation, said valve device besub'je'ct to the control of said valve means in such a manner as to "be maintained in a position continuing the supply of fluid under-pressure to cause the sanding operation, notwithstanding the cessation of the wheel slip condition until such time as said valve means operates to'restore the degree of application of the brakes .to 'a higher degree, and means selectively conditionable to cause :the sanding operation to be either promptly terminated or to continue Iindefiniteh following the operation of the valve device to terminate the supply of .fluid under pressure to causesanding.

1'6. In a' vehicle brake and sanding control appara'tus, the combination of means responsive to the slipping :conditi'on of a wheel of the vehicle occurring while the brakes are applied thereon, valve means controlled by .said wheel slip responsivemeans and operative upon the occurrence of the slipping condition-toefiect reduction in the degree o'frapplication of the brakesacting on said 'wheel 1to:a certain low degree and thereafter to restore the degree of application to a higher degree, a sanding control valve device operative in'response to the supplyvof fluid'under pressure thereto and the-maintenance of -a predeterminedpressure therein to cause a sanding operationa valve devicecontrolled bysaid wheel slip responsive means and operative in response to the initiation of a slipping condition to cause fluid under pressure to be supplied to said sanding control valve device, said valve device being subject tothe control of the valve means :in such a manner as'to continue'the supply of fluid under'pressure to the sanding control valve device until such time as said valve means is operated torestore the degree'of application of the brakes to a higher degree, and means in the communication through which fluid under'pressure'is supplied '-to the sanding control valve device effective upon termination 0f the supply of fluid under pressure to *the sanding :control valve device to effect a promptzreduction of the pressure :acting thereon to a value below that required to maintain the sanding control valve device operative to effect the sanding roperation.

1'7. in 'a vehicl brake and sanding control apparatus, the combination "of means responsive toflh'e slipping condition of a wheelpf vthe'v'eliicl'e occurring while the brakes are appiied'thereon, valve aneans lC'OlfltI'Oll'Bd by saidwheel slip responsive means and operative upon :the occurrence of the slipping condition "to 'feffect reductioniin the degree of application "of the brakes acting :on saidwheelto .a certain "low :degree and thereafter to restore the degree of application "to a higher degree; a sanding control valve device operative in response to the supply ofilu'id under pressure thereto andthe maintenance of a predetermined pressure therein to cause a sanding operation, a valve device controlled by said wheel slip respons'ive means and. operative in response to the initiation of a slipping condition to cause fluid under pressure 'to be supplied to said sanding control valve device, said'valvedevice being subject to the control of the valve .means in such a manneras to continue the supply of .fluid'under pressure tothe sanding control valve device until such time as said valve means is operated to restore the degree of application of the brakes to a higher degree, and selectively conditionable means controlling the communication through which fluid under pressure is supplied to the sanding control valve to alternatively release or prevent th releaseoi fluid under pressure therefrom. e l 1 .18. In a vehicle brake and. sanding control apparatus, the combination offluid pressure operated valve means normally in aaposition establishing a [communication through which .fluid under pressure maybe supplied toefiect abrake application on a wheel of the vehicle :and operative, .in response to a certain variation of .a control fluid pressure, to :a diffierent position :to establish an exhaust communication through which fluid under pressure is released to cut ofi said supply communication and establish an exhaust com- 27 munication through which fluid under pressure is released to effect a reduction in the degree of brake application effective on said wheel, a fluid pressure operated device subject to said control fluid pressure and operatively responsive to said certain variation of the said control fluid pressure for effecting a sanding operation, and means operatively responsive to a predetermined rotative condition of the said vehicle wheel for effecting said certain variation of the said control fluid pressure.

19. In a railway vehicle brake and sanding control apparatus, the combination of fluid pressure operated valve means normally in one position establishing a communication through which fluid under pressure may be supplied to effect a brake application on a wheel of the vehicle and operative, in response to a certain variation of a control fluid pressure, to a different position to cut off said supply communication and to establish an exhaust communication through which fluid under pressure is released to effect a reduction in the degree of brake application effective on said Wheel, a fluid pressure operated device subject to said control fluid pressure and operatively responsive to said certain variation of the control fluid pressure for effecting a sanding operation, valve means carried by the axle journal associated with said vehicle wheel and operatively responsive to a predetermined rotative condition of the wheel, and means providing a fluid pressure communication between said valve means and said fluid pressure operated valve means whereby to effect said certain variation of the said control fluid pressure whenever said certain predetermined rotative condition of the vehicle wheel occurs.

20. In a vehicle brake and sanding control apparatus, the combination of fluid pressure operated valve means normally in a position establishing a communication through which fluid under pressure may be supplied to effect a brake application on a wheel of the vehicle and operative, in response to a certain variation of a control fluid pressure, to a different position in which it cuts off said supply communication and establishes an exhaust communication through which fluid under pressure is released to effect a reduction in the degree of the brake application effective on said wheel, sanding control means, fluid pressure operated switch means operatively responsive to said certain variation of the control fluid pressure for said fluid pressure operated valve means for effecting operation of said sanding control means, and means for effecting said certain variation of the control fluid pressure for said fluid pressure operated valve means.

21. In a vehicle brake and sanding control apparatus, the combination of valve means normally in one position establishing a communication through which fluid under pressure may be supplied to effect a brake application on a wheel of the vehicle and operative to a different position in which it cuts off said supply communication and establishes an exhaust communication through which fluid under pressure is released to effect a reduction in the degree of the brake application effective on said wheel, switch means having a normal inactive position and operative to an active position, means responsive to operation of said switch means to its active position for effecting a sanding operation, and a common fluid pressure responsive means operatively responsive to a certain variation of a control fluid 28 pressure for effecting simultaneously the operation of said valve means to its said different position and the operation of said switch means to its active position.

22. In a vehicle brake and sanding control apparatus, the combination of valve means normally in one position establishing a communication through which fluid under pressure may be supplied to effect a brake application on a wheel of the vehicle and operative to a different position in which it cuts off said supply communication and establishes an exhaust communication through which fluid under pressure is released to effect a reduction in the degree of the brake application effective on said wheel, switch means having a normal inactive position and operative to an active position, means responsive to operation of said switch means to its active position for effecting operation, a common fluid pressure responsive means operatively responsive to a certain variation of a control fluid pressure for effecting simultaneously the operation of said valve means to its said different position and the operation of said switch means to its active position, and means responsive to a predetermined rotative condition of the said wheel for effecting said certain variation of the control fluid pressure for said fluid pressure responsive means.

23. In a vehicle brake and sanding control apparatus of the type having a control pipe chargeable with fluid at different pressures in accordance with the degree of the brake application desired and a brake cylinder chargeable with fluid at a pressure corresponding to that established in the control pipe to effect a corresponding degree of brake application on one or more wheels of the vehicle, the combination of fluid pressure operated valve means interposed between said control pipe and said brake cylinder and normally in one position establishing a communication through which fluid under pressure may be supplied from said control pipe to said brake cylinder to effect a brake application to a corresponding degree and operatively responsive to a certain variation of a control fluid pressure to a different position in which said supply communication is cut off and an exhaust communication is established through which fluid under pressure in the brake cylinder is released to effect a reduction in the degree of the brake application associated with the said vehicle wheel or Wheels, a sanding reservoir, a sanding control valve device normally in one position establishing a charging communication for said sanding reservoir and operative to a different position cutting off said charging communication for the sanding reservoir and establishing a supply communication through which fluid under pressure is supplied from the sanding reservoir to effect a sanding operation, and fluid pressure responsive means subject in opposing relation to fluid pressure in two chambers on opposite sides thereof, one of said chambers being chargeable with fluid at a pressure corresponding to that in the control pipe and the other of said chambers being chargeable with fluid at a pressure corresponding to that in the brake cylinder, said fluid pressure operated valve means being effective, when operated to effect a reduction of the pressure in the brake cylinder, to also effect reduction of pressure in the said other chamber whereby to produce a fluid pressure differential on said fluid pressure operated device effective to maintain said sanding control valve device in 29 its said different position at least as long as the reduction in brake cylinder pressure by said fluid UNITED STATES PATENTS pressure operated valye means continues. Number Name Date 608,100 Bixby July 26, 1898 GEORGE NEWELL 5 951,312 Hartman Mar. 8, 1910 2,198,022 Aikman Apr. 23, 1940 REFERENCES CITED ,198,031 Farmer Apr. 23, 1940 2,208,739 Hines July 23, 1940 The following references are of record in the 2,243,450 Aikman May 2'7, 1941 file of this patent: 10 2,366,044 McCune Dec. 26, 1944 

